It has been proposed recently that insulin is the link between obesity, hypertension, and glucose intolerance. Both obesity and glucose intolerance are associated with increased insulin resistance, hyperinsulinemia, and increased prevalence of hypertension. In addition, patients with essential hypertension are insulin, resistant and hyperinsulinemic. Therefore, it has been postulated that insulin might play a role in the pathogenesis of hypertension through stimulation of the sympathetic nervous system, promoting renal sodium retention, or affecting cation transport. The relationships between insulinemia, obesity, glucose intolerance and hypertension have been studied in 2873 Pimas. Among subjects not taking antihypertensive drugs, neither fasting nor post-load serum insulin concentrations were related to blood pressure. Thus these findings do not support the hypothesis of a role for insulin in determining hypertension or regulating blood pressure in the Pima Indians.